<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="x-ua-compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width,initial-scale=1.0">
    <!--上诉3个meta标签 必须 放在最前面，任何内容都 必须 跟随其后-->
    <title>7.3栅格系统</title>
    <link href="lib/bootstrap/css/bootstrap.min.css" rel="stylesheet">
    <style>
        div {
            border: 1px solid #000000;

        }
    </style>
</head>
<body>
<!--设置栅格布局-->
<div class="container"><!--或者container-fluid-->
    <div class="row">
        <div class="col-xs-4">.col-xs-4</div>
        <div class="col-xs-4">.col-xs-4</div>
        <div class="col-xs-4">.col-xs-4</div>
    </div>
    <div class="row">
        <div class="col-sm-4">.col-sm-4</div>
        <div class="col-sm-4">.col-sm-4</div>
        <div class="col-sm-4">.col-sm-4</div>
    </div>
    <div class="row">
        <div class="col-md-4">.col-md-4</div>
        <div class="col-md-4">.col-md-4</div>
        <div class="col-md-4">.col-md-4</div>
    </div>
    <div class="row">
        <div class="col-lg-4">.col-lg-4</div>
        <div class="col-lg-4">.col-lg-4</div>
        <div class="col-lg-4">.col-lg-4</div>
    </div>
    <span>col-xs-4:指小于768px的小设备</span><br>
    <span>col-sm-4:指大于等于768px的设备</span><br>
    <span>col-md-4:指大于992px的设备</span><br>
    <span>col-lg-4:指1200px的设备</span>
</div>
</body>
</html>